In prior art, when a child car seat is installed onto a car seat within a car for use, the child car seat is fixed relative to the car seat, and a safe belt tied to the child car seat performs buffer action when accident such as collision happens. However, the safe belt can only protect the child in the car seat via buffering and shock absorbing actions, but can scarcely protect the car seat itself. Generally, a child car seat includes a seat and a base fixedly connected together, and in actual use, when collision occurs, the seat will wobble relative to the base due to inertia so as to that the connected location between the seat and the base is prone to deform or even break.